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Date: Thu, 16 Jun 2011 15:00:39 -0700
From: Andi Kleen <ak@linux.intel.com>
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Subject: Re: REGRESSION: Performance regressions from switching anon_vma->lock
 to mutex
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Shaohua Li <shaohua.li@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Hugh Dickins <hughd@google.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, David Miller <davem@davemloft.net>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Russell King <rmk@arm.linux.org.uk>, Paul Mundt <lethal@linux-sh.org>, Jeff Dike <jdike@addtoit.com>, Richard Weinberger <richard@nod.at>, "Luck, Tony" <tony.luck@intel.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>, Namhyung Kim <namhyung@gmail.com>, "Shi, Alex" <alex.shi@intel.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "Rafael J. Wysocki" <rjw@sisk.pl>


> Ok, I bet it doesn't make them a non-issue, but if doing this in
> anon_vma_clone() helped a lot, then doing the exact same pattern in
> unlink_anon_vmas() hopefully helps some more.
Hi Linus,

I did essentially the same thing (just in a less elegant, more paranoid 
way) in my old
batching patches.

http://comments.gmane.org/gmane.linux.kernel.mm/63130

They made it a bit better, but overall it's still much worse than 2.6.35 
(.36 introduced the
root chain locking). I guess we'll see if it can recover mutex though, 
but I'm not
optimistic.

-Andi

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